This study utilized SEM to examine the fiber structure of cotton stock fabrics and tested their durability based on ISO standards. Two types of cotton stock fabrics were evaluated: natural-colored (162 cm width, 120.8 g/m2 weight, 281/10 in × 252/10 in density) and black-colored (157 cm width, 136.1 g/m2 weight, 482/10 in × 210/10 in density). Prolonged water immersion caused surface yarns to loosen, fibers to expand, and the cross-sectional area to increase. Residual pulp and impurities on the fabric adhered to fibers. After 27 days, fiber looseness peaked, leading to complete breakdown after 30 days. Natural-colored fabric experienced significant weft strength loss within 12 days, while black fabric showed slightly higher weft strength loss after 36 days. Color changes were prominent in natural-colored fabric during the initial 21 days, while black fabric displayed noticeable changes after 12 days of immersion.